QUESTION: Is solar energy the answer to our energy needs?
ANSWER: The sun has the tremendous power to provide for all of our energy needs. In a single hour, the sun has enough output to power the Earth for a whole year. Properly harnessing this incredible source could solve the energy crisis forever. We often hear that solar energy is free energy. Well, there is an element of truth to that sentiment, but we need to look deeper into the solar cell industry.
Solar cells, or photovoltaic cells, are made of semiconductors, the most common being silicon. Sunlight hitting the solar cells is absorbed by the semiconductor. The absorbed energy loosens electrons in the material and this flow constitutes an electric current.
Solar panels start as quartz, the most common form of silica, and is refined into silicon. The quartz is extracted from mines, and that mining exposes miners to the deadly occupational hazard of the lung disease called silicosis.
Since 2008, manufacturing of solar panels has moved from the United States, Europe, and Japan to China, Malaysia, Taiwan, and the Philippines. Today, half of all solar panels are made in China. Cheap labor, you understand. Safety rules and regulations for miners in China lag far behind those of the United States and European countries.
Water is another problem. Photovoltaic manufacturing requires tons of water for chemical processing, dust control during construction, air pollution control, and cleaning during installation.
There has been a quiet revolution in how solar panels are made. Makers of thin-film cells deposit layers of semiconductor material directly on a substrate of glass, metal, or plastics, instead of the older technique of slicing wafers from a silicon slab. Thin-film technology reduces waste and is more environmentally friendly.
Some thin-film solar panels use cadmium, a known and nasty carcinogen. Cadmium is also a genotoxin, meaning it can cause inheritable mutations. First Solar, a company based in Tempe, Arizona, is very careful about protecting its employees exposed to cadmium during manufacturing. But little is known about workers exposed to cadmium in the early stages of the life cycle of the metal, from the zinc mines where it comes from, through the smelting process that makes it pure, and the process that turns it into semiconductor material ready to use in panels.
Going “green” has a price. Analysts judge the impact of the energy used to make a solar panel compared to the amount of carbon generated in the production of that energy. The so-called carbon footprint can be considerable.
There is the payback period, the time it takes for a system to recover the energy used to produce it. That can be several years. The other payback to consider is the financial payback. If you install solar cells on your roof, you want the system to pay for itself eventually. The financial payback can be several years, stretching into decades.
Many people who install solar cells do not really care that much about the financial payback. They may want to help the United States get a handle on climate change. They also want our country to not depend on foreign oil supplies.
Some people see solar as a panacea for our energy woes, considering how “dirty” various fossil fuels have proven to be. Indeed, solar photovoltaic cells have a bright future. But we should not turn a blind eye to the darker side of this new technology. All energy sources have their pluses and minuses, good and bad. It is not possible to stop paying for energy.
In the 1950s there were scientists saying that with the advent of nuclear power plants, electricity would be so cheap there would be no need to meter it. We hear the same rosy predictions for solar photovoltaic cells. In the final analysis, there is no such thing as a free lunch when it comes to meeting our energy requirements.
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Larry Scheckel is a retired Tomah High School physics teacher.